In fiction, engineering, and thought experiments, unobtainium is any fictional, extremely rare, costly, or impossible material, or (less commonly) device needed to fulfill a given design for a given application. The properties of any particular unobtainium depend on the intended use. For example, a pulley made of unobtainium might be massless and frictionless; however, if used in a nuclear rocket, unobtainium might be light, strong at high temperatures, and resistant to radiation damage. The concept of unobtainium is often applied flippantly or humorously. For instance, unobtainium is described as being stronger than steel, and lighter than helium[where?].

Contents

Since the late 1950s,[a][1] aerospace engineers have used the term "unobtainium" when referring to unusual or costly materials, or when theoretically considering a material perfect for their needs in all respects, except that it does not exist. By the 1990s, the term was in wide use, even in formal engineering papers such as "Towards unobtainium [new composite materials for space applications]."[2][3]
The word unobtainium may well have been coined in the aerospace industry to refer to materials capable of withstanding the extreme temperatures expected in re-entry.[1]Aerospace engineers are frequently tempted to design aircraft which require parts with strength or resilience beyond that of currently available materials.

Later, unobtainium became an engineering term for practical materials that really exist, but are difficult to get.[4] For example, during the development of the SR-71 Blackbird spy plane, Lockheed engineers at the "Skunk Works" under Clarence "Kelly" Johnson used unobtainium as a dysphemism for titanium. Titanium allowed a higher strength-to-weight ratio at the high temperatures the Blackbird would reach, but the Soviet Union controlled its supply and was trying to deprive the US armed forces of this resource.[b]

"Unobtainium" has come to be used as a synonym for "unobtainable" among people who are neither science fiction fans nor engineers to denote an object that actually exists, but which is very hard to obtain either because of high price (sometimes referred to as "unaffordium") or limited availability. It usually refers to a very high-end and desirable product; for instance, in the mountain bikingcommunity, "These titanium hubs are unobtainium, man!" Old-car enthusiasts use "unobtainium" to describe parts that are vanishingly rare or no longer available.[9][10]

In maintaining old equipment, unobtainium refers to replacement parts that are no longer made, such as parts for reel-to-reel audio-tape recorders or rare vacuum tubes that cost more than the equipment they are fitted to (especially true of certain vacuum tubes, such as the 1L6, used almost exclusively in American battery-powered shortwave radios or the WD-11 used in certain early 1920s radios). Similarly, parts for classic & vintage Ferraris are made by a company actually named Unobtainium Supply Co.[11]

There have been repeated attempts to attribute the name to a real material. Because of the long-standing usage of the term "unobtainium" within the space elevator research community to describe a material with the necessary characteristics,[12][13]LiftPort Group President Michael Laine has advocated assigning the term as the generic name for cables woven of carbon nanotube fibers, which seem to satisfy the requirements for this application. Since he claimed that sufficiently long nanotube cables will be prohibitively expensive to develop without inexpensive access to microgravity, these cables would still be close enough to unobtainable to meet the definition. However, this usage does not seem to have become widespread. The eyewear and fashion wear company Oakley, Inc. also frequently denotes the material used for many of their eyeglass nosepieces and earpieces, which has the unusual property of increasing tackiness and thus grip when wet, as unobtanium.

Unobtainium can refer to any substance needed to build some device critical to the plot of a science fiction story but which does not exist in the universe as we know it. A hull material that gets stronger by absorbing and converting heat and pressure into energy in the film The Core (2003) was nicknamed unobtainium, but the concept under different names can be seen in the anti-gravity material cavorite from H. G. Wells' 1901 novel The First Men in the Moon, as well as the super-strong material scrith from Larry Niven's novel Ringworld, which requires a tensile strength (i.e. chemical bonds) on the order of the force binding an atomic nucleus.

Unobtainium can also refer to any rare but desirable material used to motivate a conflict over its possession, making it a MacGuffin (it appears in the story as something to obtain, not something that is significantly used).

Unobtainium can be used in a disparaging context (e.g., "That idea is silly; you'd need unobtainium wires to hold the planet up!") or a hypothetical one ("If one were to build an unobtainium shell around a black hole's event horizon, what would happen to the material piling up on it?").

The term handwavium (suggesting handwaving) is another term for this hypothetical material, as are buzzwordium, impossibrium, hardtofindium, and less commonly, phlebotinum.[15]

The term eludium (also spelled with variants such as illudium) has been used to describe a material which has eluded attempts to develop it. This was mentioned in several Looney Tunes cartoons, where Marvin the Martian tried (unsuccessfully) to use his "Eludium Q-36 Explosive Space Modulator" to blow up the Earth.

Another largely synonymous term is wishalloy,[16] although the sense is often subtly different in that a wishalloy usually does not exist at all, whereas unobtainium may merely be unavailable.

^"unobtainium, n. A substance having the exact high test properties required for a piece of hardware or other item of use, but not obtainable either because it theoretically cannot exist or because technology is insufficiently advanced to produce it. Humorous or ironical." Listed in "Interim Glossary, Aero-Space Terms," as compiled by Woodford Heflin and published in February 1958 by the Air University of the US Air Force.

^Relatively large amounts of titanium are used in aircraft such as the F-15, F-18, and F-22 fighters and the B-1 bomber.

^Jones, Richard (2010-01-10). "EXCLUSIVE: Inside China's secret toxic unobtainium mine". Mail Online. Retrieved 2010-06-04. The rare-earths blasted out of rocks here [ Baiyun Obo ] feed more than 77 per cent of global demand... 'Dysprosium, for instance, allows systems to work under extreme conditions,' he explained. 'The US military doesn't want to buy it on the open market. They need a guaranteed supply and it's becoming a problem.

^This property of Unobtanium is stated in movie guides, rather than in the film. Wilhelm, Maria; Dirk Mathison (November 2009). James Cameron's Avatar: A Confidential Report on the Biological and Social History of Pandora. HarperCollins. p. 4. ISBN0-06-189675-6.